Abstract: An instrument including a light-emitter for emitting a light beam, a sensing head portion through which the light beam is transmitted, a light-detective element receiving the beam from the head portion, and a detector receiving an electric signal from the light-detective element. The head portion has a thermo-optical element for changing a first component of the light beam with an ambient temperature, and an optical element for changing a second component of the beam with an electric quantity. The electric signal produced by the light-detective element has a first and a second component which correspond to the first and second components of the light beam, respectively. The detector determines the ambient temperature based on the first component of the electric signal, and determines the electric quantity based on the second component of the electric signal. The electric quantity may be an AC magnetic field, a current, an AC electric field or a voltage.

Abstract: A method of manufacturing an optical isolator which has a rotator capable of rotating a plane of polarization by the Faraday effect, and a polarizer of multilayer structure formed of alternately superposed transparent dielectric films and films having a complex dielectric constant, includes the steps of: forming the rotator as a plate having a large area and the polarizer as an array having a large area; forming an optical isolator array by attaching the polarizer array at least to one surface of the rotator plate in such a manner that the layers of the polarizer array extend perpendicularly to the surface of the rotator plate; and cutting the optical isolator array into a plurality of optical isolator chips.